I don't know what to say about the casting number... the date code and engine serial number would be consistent with a very late '55 2nd series truck or a '55 engine sn in a '56. The dowel appears to be in the position that does not support full flow filtering, which would be consistent with the practice at the earlier '56 casting date. At least you know it's a 261!
Last edited by drdoug; 03/15/2019 1:38 AM.
